Statistical element counter



Nov. 26, 1963 J. LEUSCHNER ETAL 3,111,768

STATISTICAL ELEMENT COUNTER Filed D80. 13, 1960 3 Sheets-Sheet l Illlllllllllllllllll Nov. 26, 1963 I J. LEUSCHNER ETAL 3,111,768

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1963 J. LEUSCHNER ETAL 3,111,768

STATISTICAL ELEMENT COUNTER Filed Dec. 15, 1960 s Sheets-Sheet s IN V EN TOR.

United States Patent 3,111,768 STATISTECAL ELEMENT C(BUNTER .lohannes Leuschner and- Hans Schluge, Heidenheim (Brenz), Germany, assignors to Carl Zeiss, Oberkochen, Wurtternberg, Germany Filed Dec. 13, 1960, Ser. No. 75,528 14 Claims. (61. 33--178) The present invention relates to improved apparatus for analyzing the statistical distribution of particle sizes in a photomicrograph of a mixture of particles.

In one of the apparatus known to the art for the statistical evaluation of particle size (e.g., the breakdown of a photograph of a mixture of difierent sized particles into a distribution curve according to size), a light spot of adjustable diameter is projected on the photograph. The spot diameter may be changed in increments by adjustment of an iris diaphragm. A counter is associated with each specific selectable diameter, and as the spot coincides with each element corresponding to the selected diameter, the associated counter is manually actuated. A marking hammer is simultaneously operated to mark the counted element.

The particles in the photograph (e.g. a photomicrograph) are thus classified into groups of sizes and the number of particles in each size group is counted.

' Two ditliculties are encountered in such measurements with the apparatus known to the First, those particles the dimensions of which fall at the boundary between two size groups cause difiiculty with respect to classification.

Second, the range of sizes in each size group is equalv so that the number of particles of each size can be plotted directly as a distribution curve of particle size. By so doing, however, the relative accuracy of sorting is substantially less with small particles than with larger particles.

It is, therefore, the primary object of this invention to provide improved apparatus obviating the disadvantages of the prior art.

In accordance with this'object, there is provided, in a preferred embodiment of this invention, a translucent table upon which the photograph of the mixture of parti cles can be placed. A spot of light of variable diameter is projected on the table. A plurality of counters are provided to count the particles falling within a specific size increment or step.

The range of sizes in each increment or step is variable in accordance with the specific problem. The range sizes in each increment or category can be varied with the mean particle size in the category to make accuracy of sorting constant. Thus, tor example, the range of sizes can be increased exponentially with the particle size to make the accuracy of sorting of small and large particles equal. Alternatively, if the particle size distribution peaks around one size, the size increments can be narrowed about the peak to give the highest counting accuracy at such peaks.

For this purpose, there is provided means for varying the transmission ratio between the diaphragm setting member and the iris diaphragm. By varying the transmission ratio during the course of the measurement, the result is obtained that the relationship between the rotation of the diaphragm setting member and the aperture of the iris diaphragm is no longer linear. This means that the width of the aperture interval of the iris diaphragm associated with the individual counters and thus also the width of the categories is changed.

If it is desired, for instance, to measure the particies with relatively constant precision by classification in a predetermined number of categories, the category diameters must increase exponentially with their number. If,

3,111,768 Patented Nov. 26, 1963 however, one is confronted with particle mixtures which have a clear frequency maximum at a given diameter or some other linear dimension, one will strive for a particularly high precision in measurement around this maximum, while the precision of measurement in front of and behind the maximum can be smaller. For this reason, by suitable selection of the transmission ratio between diaphragm setting member and iris diaphragm, the categories will be selected as narrow as possible around the maximum and the categories in front of and behind the maximum will be made correspondingly wider. Furthermore, a plurality of other transmission ratios adapted to the specific measurement problem can be established.

To prevent errors in particle counts, means are provided to reduce the space between increments or categories to zero. Thus, when a particle is of such size as to be on the border line between adjacent categories, it will be counted in one of the categories. Thus, no particle will be omitted from the count. This is accomplished by a distribution circuit to the individual counters which always activates one of two counters for adjacent increments.

Distribution of counting pulses to the counters is preferably accomplished through a rotary commutator. Two sliding contacts, the distance between'which is greater than the insulating path between two commutator segments, ride on the commutator and switch devices are provided which, upon the depression of the release button for the closing of the counter circuit, select the sliding contact which is not at the time on an insulating path. In this apparatus, therefore, one of the sliding contacts is always definitely on a commutator segment and upon the recording process, this sliding contact which is on the commutator segment and thus the counter associated with said contact are selected. The result is thus obtained that for all practical purposes, the distance between the categories is made zero.

The command to switch from one sliding contact to the other can be obtained either directly on the rotary commutator or a second circuit can be provided for this purpose.

The invention will be more clearly understood by reference to the following description taken in combination with the accompanying drawings, of which:

FIG. 1 is a simplified perspective view of a particle size counter in accordance with the present invention;

iF-IG. 2 is a partial section through the apparatus of FIG. I, seen from above;

FIG. 3 is a partially broken away top view of the cam disc and the gearing arranged between the diaphragm setting member and the iris diaphragm;

FIG. 4 is a section along the line IV-IV of FIG. 3;

FIG. 5 is a schematic diagram of a circuit for switching from one sliding contact to the other, in connection with which the command for the switching of the sliding con tacts is obtained in a separate circuit; and

FIG. 6 is a schematic diagram of a circuit for switching from one sliding contact to the other, in which the switch ing command is obtained directly at the commutator.

In FIG. 1 there is shown a particle size counter comprising a surface 1 to receive the copy for evaluation and an upstanding frame 2 to receive the individual counters 3. The WOTd copy as used herein, means the physical representation of a plurality of measurable particles of different sizes. For example, the copy may consist of an electron micrograph of particles of varying size in a dispersed system (e.g. an aluminum hydroxide sol). In the case shown here, forty-eight individual counters 3 as well as a totalizer counter 4 are provided. The window 5 serves to indicate the operating condition of the apparatus. The supporting surface 1 contains a ground glass disc 6, the central part 7 of which is transparent. The

ground glass disc 6 is illuminated from sources within the counter.

Hand wheels 8 and 9, coupled rigidly to each other, are provided to adjust the aperture of the iris diaphragm and, thus, the size of the spot projected on the transparent portion 7 of table 1. Lever 10 carries a marking pencil 11. A foot pedal 12 is provided to trip the counter associated with the selected size of element being counted when the element coincides with the projected spot. Upon tripping of the pedal, the counter is actuated and the lever 10 is automatically moved down so that the counted element is marked by pencil 11.

Referring to FIGS. 2, 3 and 4, there is shown a shaft 13 connecting the handwheels 8 and 9. Gear 14 is mounted on shaft 13 and engages pinion 15. Pinion 15 rotatably drives an auxiliary commutator 16 on which a sliding contact 17 slides. A magnetic brake 13 is provided to selectively lock gear 15 and thus handwheels 8 and 9 at a predetermined angular position.

On shaft '13, there is supported in axially displaceable manner a hollow shaft 51, which is firmly connected with a worm gear 52. The hollow shaft 51 is guided linearly by a groove 53 and a pin 54 and at the same time coupled fast to the shaft 13 with respect to rotation. The worm gear 52 engages a spirally toothed gear 55 arranged on the tube 19. Upon rotation of the handwheel 8, therefore, the aperture of the iris diaphragm 20 is varied via the two gear parts 52, 55.

It is readily clear that the worm gear 52 can also be developed as an obliquely toothed gear.

To the hollow shaft 51, there is connected a transmission member 56, which, in the position shown in FIG. 2, rolls on the front limiting line of the hollow cylinder 57. By means of a spring 58, the transmission member 56 is at all times pulled towards the right.

In the hollow cylinder 57, there is arranged a cylindrical cam 59 which is provided with a groove 60. Into this groove there extends a pin 61 which is arranged in a part 62. The part 62 is rotatable by means of the knob 63 around the shaft 64.

In the position shown in FIG. 2, the transmission member 56 rolls on the front limiting line of the hollow cylinder 57 and no axial displacement of the worm gear 52 occurs. In this way, there is linear dependence of the apenture of the iris diaphragm 20' on the rotation of the handwheel 8. If the cam disc 59 is brought into the position shown in FIG. 3, by turning the knob 63, then the transmission member 56 moves on the cylindrical cam disc. Therefore, in this case, upon turning the handwheel 8 a rotation of the worm gear 52 and a simultaneous axial displacement of said worm gear are obtained.

A commutator 65, comprising conductor segments 23 separated by insulation segments 24, is mounted on shaft 13. The four sliding contacts 25, 26, 27 and 28 slide on the commutator 65.

If the handwheel 8 is turned in clockwise direction thenas can be noted from FIGS. 3 and 4the aperture of the iris diaphragm will be increased Upon this rotation of the handwheel 8, the transmission member 56 travels into the valley of the cam 59; other words, the worm gear 52 is moved from left to right under the action of the spring 58. This axial movement of the worm gear 52 adds onto the rotation so that thenefore, there corresponds to a given range of angular rotation of the handwheel 8 an aperture range of the diaphragm 20 which is larger than if there were no axial displacement.

Correspondingly, upon rotation of the handwheel 8 in counterclockwise direction from the position illustrated, the aperture of the iris diaphragm is reduced in size and, since member 56 travels to the peak of the cam 59, the worm gear 52 is moved from right to left. In this case, the axial movement is subtracted from the rotation and the iris diaphragm 20 is closed more slowly than would be the case if the tnansmission member 56 were to move on the hollow cylinder 57.

Thus, it can be seen that the incremental change in the aperture of the iris diaphragm 20 by fixed increments of angular rotation of the handwheel 8 increases greatly with an increase in the aperture of this diaphragm. With suitable development of the cam disc 59 there is obtained an exponentially increasing width of step, i.e., the width of the categories increases exponentially with their ordinal ntunber. However, the counters are associated with fixed increments of handwheel rotation. Thus, particles of small diameter are measured with greater absolute prccision than particles of a larger diameter, and the relative precision can be constant over the entire measurement range.

By suitable development \of the cylindrical cam disc 59, other dependencies between the rotation of the handwheel 8 and the aperture of the iris diaphragm 20 can also be established. For instance it is possible to obtain a particularly high precision of measurement around a given maximum of a particle size distribution, i.e., therefore a small aperture range of the iris diaphragm for a given angle rotation of the hlandwheel 8 and to select a smaller precision of measurement in front of and behind this maximum.

FIG. 5 shows a circuit by which the distance between successive aperture intervals of the iris diaphragm 20 is made zero.

In FIG. 5, 3-,, 3 3 3 etc. are the individual counters. The individual commutator segments bear the numbers 23- 23 23 23 etc. The totalizer mechanism is marked 4 in the same way as in FIG. 1. 34) are series resistors while 31 is the rectifier for the counting circuit and 32 is a switch.

Parallel to the counting circuit proper, there is connected another circuit which contains the foot pedal switch 12. The foot switch itself consists of the two switches 33 and 34, the switch 34 being delayed somewhat with respect to the switch 33'. Another switch 35 serves to shunt the switch 33. In the circuit connected with the switch 34, there is provided a rectifier 70 as well as an electro-magnet 36 which serves to move the marking lever 10.

To the switch 33 there is connected a transformer 3-7 which via a rectifier 38 provides the magnetic brake 18 with current. Furthermore, there is connected to the switch 33 a relay 39 which is connected in series with the auxiliary commutator 16.

The manner of operation of the apparatus shown in FIGS. 2 and 5 is as follows. First of all, by turning the handwheels 8 and 9, the correct aperture of the iris diaphragm 20 is set. During this setting movement, the commutator 65 turns with respect to the sliding contacts 25, 26, 27 and 28. At the same time, the auxiliary commutator 16 turns with respect to the sliding contact 17. It can be noted directly from FIG. 5 that the distance between the sliding contacts 25 and 26 and 27 and 28 respectively is established to be greater than the length of an insulating gap 24.

After completion of the setting of the iris diaphragm, the foot switch 12 is actuated. Closure of switch 35 energizes the magnetic brake 18 and locks the handwheels 8 and 9.

At the same time, a current flows, in the case shown here, over the sliding contact 17 through the auxiliary commutator 16 and the relay 39. The sliding contact of the auxiliary commutator is on a com-mutator segment since the main sliding contact 25- of the main commutator 22 is on an insulation gap 24. As soon as current flows through the relay 39, the switch 40 is closed and the switches 41 and 42 are actuated by conventional relays (not shown) to contact the sliding contacts 26 and 28 at the main commutator 22.

Upon the closing of the switch 34, the electro-magnet 36 receives current. The energized electro-magnet simultaneously pulls down the marking lever 10 to mark the particle evaluated and closes the switches 35 and 32.

By the closing of switch 35, switch 33' is shunted so that the foot switch can be let go without immediately cutting off the holding current to the magnetic brake I8 and the relay 39.

By the closing of the switch 32, current flows via the rectifier 31 and the series resistors 30 to the sliding contact 26 and from there via the commutator segment 23 through the counter 3 From here, the current flows via the commutator segment 23 and the sliding contact 28 back through the totalizer 4 Therefore, in this case, the counter 3 and the totalizer 4 respond.

If, in FIG. 5 the four sliding contacts 25, 26, 27 and 23 were imagined displaced somewhat further towards the left, then the main sliding contact 25 rests on the commutator segment 23 The slider 17 on the auxiliary commutator 16 has then moved so far forward that it res-ts on an insulating gap. Therefore, upon the recording process the relay 39 is not actuated so that the switches 41 and 42 remain in the rest position shown. The current in this case flows via the sliding contact 25 through the counting mechanism 3 and back through the sliding contact 27.

In the circuit shown in FIG. 6 only two sliding contacts 43 and 44 are provided. The switch 45 lies in rest position on the contact 43, so that therefore this sliding contact is to be considered the main sliding contact. A resistor 47 is placed in series with the switch 45 and the associated contact 43 or 44. A relay 46 is connected parallel to the counting circuit and serves to actuate the switches 45 and 49.

The manner of operation of the circuit shown here is as follows. Upon depressing of the foot switch 12, the switch 48 is closed. As a result of this, current flows in the case shown here through the resistor 47 and the main sliding contact 43 to the commutator segment 23 From there the current flows back through the counter 3 and the totalizer 4.

If, in the case of the circuit shown in FIG. 6-, the two sliding contacts 43 and 44 are imagined to be displaced to the right to such an extent that the main sliding contact 43 is on the insulating gap between the two commutator segments 23 and 23 then upon actuation of the loot switch 12 the entire line voltage acts on the relay 46. The relay 46 is attracted and closes the holding contact 49 as well as the switch 45. The counting circuit is now closed via the sliding contact 44 and the commutator segment 23 through the counter 3 and the totalizer 4.

It is readily clear that the precision of the circuit shown in FIG. 5 can be increased by selecting the speed of rotation of the auxiliary commutator 16 higher than the speed of rotation of the main commutator 22 and by selecting the insulating gaps of the auxiliary commutator longer in accordance with the ratio of the speeds of rotation than those of the main commutator. In this way, a switching from one sliding contact to the other is def initely effected already when the main sliding contact just slides beyond a commutator segment.

This invention may be variously modified and embodied within the scope of the subjoined claims.

What is claimed is:

1. Apparatus for recording the number of particles falling within each of a plurality of size increments in a physical representation of a plurality of measurable particles of different sizes, comprising means including an iris diaphragm for projecting a spot of variable diameter on the physical representation, a plurality of counters, means for selectively actuating a counter, a commutator for coupling said actuating means to each of said counters sequentially as a function of the angular rotation of said commutator, cam means for changing the iris phr g p re a a non-linear function. o

rotation of said commutator, and brush means associated with said commutator for coupling said actuating means to a counter simultaneously with disconnecting said actuating means from the next adjacent counter.

2. Apparatus according to claim 1 in which said cam means comprises a mechanical coupling of variable transmission ratio.

3. Apparatus according to claim 1 in which said cam means comprises a first spirally toothed gear rotatably driven with rotation of said commutator, a second spirally toothed gear engaging said first gear and coupled to the diaphragm to actuate the iris diaphragm, and a cam to axially displace said first gear.

4. Apparatus according to claim 3 in which said first gear is arranged on an axially displaceable hollow shaft, said hollow shaft being connected to a transmission member engaging said cam.

5. Apparatus according to claim 4 in which said cam comprises a cylindrical cam and which includes a hollow cylinder, said cam being displaceable axially between a first and second position within said cylinder, and means to displace said cam from first and second position.

6. Apparatus according to claim 5 in which the transmission member is so developed that, corresponding to the position of the cam, it moves either on the boundary line of the hollow cylinder causing no axial displacements or on the cylindrical cam disc itself.

7. Apparatus according to claim 3 in which said first and second gears engage in a worm drive with gear axes intersecting at 8. Apparatus according to claim 6 in which the cam disc is replaceable.

9. Apparatus according to claim 1 in which said commutator is a rotary commutator and in which said brush means comprises sliding contacts riding on said commutator, the distance between said contacts being greater than the insulating gaps between two commutator segments, and which include switch means to select the sliding contact which is on a com-mutator segment upon actuation of the counter circuit.

10. Apparatus according to claim 9 in which said switch means includes a switch which in rest condition always connects the main sliding contact into the counter circuit and :by a relay which, when said sliding contact rests on an insulating gap on the commutator and said actuating means is energized, switches the switch to the auxiliary sliding contact.

11. Apparatus according to claim 10 which includes a resistor connected in series with the sliding contacts and a relay which is connected in the circuit behind said resistor parallel to the counting circuit and which enters into operation upon application of the full line voltage.

12. Apparatus according to claim 10 which includes a second commutator which is arranged in a second circuit lying parallel to the counter circuit having a sliding contact, which is so developed and driven that its sliding contact is always on a commutator segment when the main sliding contact on the main commutator is on an insulating gap and a relay connected in series with the second commutator to switch the sliding contacts of the main commutator.

13. Apparatus according to claim 12 in which the speed of rotation of the second commutator is selected greater than the speed of rotation of the main commutator and in which the insulating gaps of the second commutator are longer, in accordance with the ratio of the speeds of rotation, than those of the main commutator.

14. Apparatus according to claim 13 which includes a relay with holding contact.

No references cited, 

1. APPARATUS FOR RECORDING THE NUMBER OF PARTICLES FALLING WITHIN EACH OF A PLURALITY OF SIZE INCREMENTS IN A PHYSICAL REPRESENTATION OF A PLURALITY OF MEASURABLE PARTICLES OF DIFFERENT SIZES, COMPRISING MEANS INCLUDING AN IRIS DIAPHRAGM FOR PROJECTING A SPOT OF VARIABLE DIAMETER ON THE PHYSICAL REPRESENTATION, A PLURALITY OF COUNTERS, MEANS FOR SELECTIVELY ACTUATING A COUNTER, A COMMUTATOR FOR COUPLING SAID ACTUATING MEANS TO EACH OF SAID COUNTERS SEQUENTIALLY AS A FUNCTION OF THE ANGULAR ROTATION OF SAID COMMUTATOR, CAM MEANS FOR CHANGING THE IRIS DIAPHRAGM APERTURE AS A NON-LINEAR FUNCTION OF ROTATION OF SAID COMMUTATOR, AND BRUSH MEANS ASSOCIATED WITH SAID COMMUTATOR FOR COUPLING SAID ACTUATING MEANS 